The invention relates to a process for producing a hollow body from a plane or conical material plate consisting of a formable material, in particular, metal. Further the invention relates to an apparatus for the practice of such a process.
A known process of metal spinning of this type is described for example in the book by W. Sellin: "Metalldrucken", 1955, pages 4 to 12. In it, a blank which is at first shaped as a plane metal disk can be clamped at its center for example between an outer chuck and a contact plate and be driven in rotation together therewith. With repeated pivotal movements of a spinning or "pushing" tool the blank is applied against the chuck step by step until the desired final form is obtained. As the spinning tool is being guided by hand or by a programmed control, a number of successive small and large pivotal movements are executed by this tool alternately toward and away from the clamped center, the pivotal movements preferably intersecting. Therefore, the waves formed in the blank by the spinning tool are shifted parallel to the respective plane of the blank, but with a directional component increasingly perpendicular to the original plane of the blank, in alternating directions toward and away from the clamped center. With some skill the spinner can thus achieve a uniform wall thickness of the formed hollow body. Yet in practice it is difficult to avoid subjecting the material of the blank to high tensile stresses in some areas. For this reason, with automatic execution of the process on program-controlled machines, only small degrees of deformation can be obtained.
The present invention is directed toward the task of providing a process for producing a hollow body wherein the occurrence of tensile stresses in the material during the fabrication thereof is, to a very large extent, avoided.
It is an object of the invention thus to provide a process for producing hollow bodies which can be carried out with greater ease and with more reproducible results than with previous processes, wherein high degrees of deformation can be attained, and which permits production of hollow bodies of any desired forms. Hollow bodies which may be produced according to the invention include bodies having different cross-sections taken lengthwise of the direction of the hollow body. Thus, the problem sought to be overcome by the invention to avoid tensile stresses occurring in the material with known processes and to cause the material to flow by exerting thereon exclusively, or at least predominantly, compressive forces may be achieved.